During milking of animals it is important to establish regularly the concentration of fat in the milk. The fat concentration varies during the milking operation, for instance the fat concentration of the milk at the beginning of the milking operation may differ from the fat concentration of the milk at the end of the milking operation. Normally the fat concentration of the milk increases during the milking operation. It is therefore often not satisfactory to take one milk sample at any point of time during the milking operation since the fat concentration of such a milk sample will probably not provide a representative value of the fat concentration of the milk extracted during the milking operation.
Furthermore, the fat is not homogeneously distributed in the milk collected in the milk container, which also makes it difficult to take a representative milk sample from the milk container where the milk extracted during one milking operation is collected. In order to solve this problem, the milk in the milk container can be mixed by means of air before the milk sample is taken. However, such a mixing creates a risk for elevated free fatty acid values (FFA).
EP-B1-1 123 651 discloses several embodiments of a milking plant. One embodiment comprises a milking member to be attached to the teats of an animal to be milked during a milking operation. A milk container is connected to the milking member and adapted to collect the milk extracted during the milking operation. The milk container comprises a measuring chamber which is filled and emptied several times during a milking operation. Pressurised air is supplied to the milk in the measuring chamber. A milk tank is connected to the measuring chamber of the milk container via a milk transport conduit and adapted to collect the milk from the milk container. A milk pump is arranged to transport the milk from the measuring chamber to the milk tank, wherein the milk is transported in separate milk portions from the milk container. The milk pump defines a suction side and a pressure side, and has a constant stroke value, i.e. the milk pump is positive displacement pump. A milk sample discharge device is connected to the pressure side of the milk transport conduit. A milk sample container is connected to the milk sample discharge device, which is adapted to permit discharge of a minor quantity of the milk extracted during the milking operation to the milk sample container.